title: Estimating the U.S. prevalence of chronic obstructive pulmonary disease using pre- and post-bronchodilator spirometry: the National Health and Nutrition Examination Survey (NHANES) 2007-2010.
abstract: BACKGROUND
  During 2007-2010, the National Health and Nutrition Examination Survey (NHANES) conducted a spirometry component which obtained pre-bronchodilator pulmonary lung function data on a nationally representative sample of US adults aged 6-79 years and post-bronchodilator pulmonary lung function data for the subset of adults with airflow limitation. The goals of this study were to 1) compute prevalence estimates of chronic obstructive pulmonary disease (COPD) using pre-bronchodilator and post-bronchodilator spirometry measurements and fixed ratio and lower limit of normal (LLN) diagnostic criteria and 2) examine the potential impact of nonresponse on the estimates.
  
  
  METHODS
  This analysis was limited to those aged 40-79 years who were eligible for NHANES pre-bronchodilator spirometry (n=7,104). Examinees with likely airflow limitation were further eligible for post-bronchodilator testing (n=1,110). Persons were classified as having COPD based on FEV1/FVC < 70% (fixed ratio) or FEV1/FVC < lower limit of normal (LLN) based on person's age, sex, height, and race/ethnicity. Those without spirometry but self-reporting both daytime supplemental oxygen therapy plus emphysema and/or current chronic bronchitis were also classified as having COPD. The final analytic samples for pre-bronchodilator and post-bronchodilator analyses were 77.1% (n=5,477) and 50.8% (n=564) of those eligible, respectively. To account for non-response, NHANES examination weights were adjusted to the eligible pre-bronchodilator and post-bronchodilator subpopulations.
  
  
  RESULTS
  In 2007-2010, using the fixed ratio criterion and pre-bronchodilator test results, COPD prevalence was 20.9% (SE 1.1) among US adults aged 40-79 years. Applying the same criterion to post-bronchodilator test results, prevalence was 14.0% (SE 1.0). Using the LLN criterion and pre-bronchodilator test results, the COPD prevalence was 15.4% (SE 0.8), while applying the same criterion to post-bronchodilator test results, prevalence was 10.2% (SE 0.8).
  
  
  CONCLUSIONS
  The overall COPD prevalence among US adults aged 40-79 years varied from 10.2% to 20.9% based on whether pre- or post-bronchodilator values were used and which diagnostic criterion (fixed ratio or LLN) was applied. The overall prevalence decreased by approximately 33% when airflow limitation was based on post-bronchodilator as compared to pre-bronchodilator spirometry, regardless of which diagnostic criterion was used.
authors.affiliation: Division of National Health and Nutrition Examination Surveys, National Center for Health Statistics, Centers for Disease Control and Prevention, 3311 Toledo Road, Hyattsville, MD 20782, USA. ttilert@cdc.gov.
authors.forename: Timothy
authors.initials: T
authors.lastname: Tilert
authors.forename: Charles
authors.initials: C
authors.lastname: Dillon
authors.forename: Ryne
authors.initials: R
authors.lastname: Paulose-Ram
authors.forename: Eva
authors.initials: E
authors.lastname: Hnizdo
authors.forename: Brent
authors.initials: B
authors.lastname: Doney
mesh_terms: D000328:Adult; D000368:Aged; D001993:Bronchodilator Agents / Q000494:pharmacology / Q000627:therapeutic use*; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys / Q000706:statistics & numerical data*; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000453:epidemiology* / Q000503:physiopathology; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013147:Spirometry / Q000706:statistics & numerical data*; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D014797:Vital Capacity / Q000187:drug effects / Q000502:physiology
chemical_list: D001993:Bronchodilator Agents